Goniometer



H 5 m l ,www f e www@ .m S Vf w Nw N065 2 wm. :MMM m um. uw mmm 2 kh rfcQV Y B F. O. CHESUS EVAL GONIOMETER A Filed-Nov. 1, 1945 Patented Mar.29, 1949 GoNroME'raa Application November-'1, 194s, serial No. 626,128

e claims. (ci. 34a-124) The present invention relates to goniometersparticularly for use with ultra or very high frequency direction nders.i

An object of the present invention is the provision of an improvedgoniometer of the capacitive type which is particularly adapted for useat ultra or very high frequencies and which is characterized byelectrical balance as well as simple mechanical construction.

Another object of the present invention is the provision for a directionfinder of a unit consisting of a motor, goniometer and sweep voltagegenerator for a cathode ray oscilloscope in which the motor is used todrive the goniometer and the generator in synchronism. The unitaccording to our invention is characterized by compact, and sturdystructure, and by the ease with which the elements of said unit may beassembled or disassembled.

Another object of the presentinvention is the provision of an improveddirection finding system embodying a goniometer and unit of the typehereinabove described and characterized by electrical balance at theoutput of the goniometer.

Other and further objects of the present invention will become apparentand the invention will be best understood from the following descriptionof an embodiment thereof, reference being had to the drawings, in which:

Fig. 1 is a schematic diagram of a direction iinder embodying ourinvention;

Fig. 2 is a sectional View, partly in elevation, of a unit including amotor, generator, and a goniometer, embodying our invention;

Fig. 3 is an enlarged detail view taken along the line 3-3 of Fig. 2;and

Fig. 4 is an enlarged detailed sectional view o the output capacitivecoupling arrangement for the goniometer, Figs. 3 and 4 having certainfeatures thereof exaggerated for the sake of clarity. Referring now toFig. 1, the direction finder there illustrated includes an antennasystem which may be in the form of an Adcock array consisting of fourmonopoles lof which units l and 2 form a spaced pair substantially atright angles to the pair formed by units 3 and t. Units l, 2, 3, 4 maybe coupled to a goniometer 5 vthrough suitable couplers Since the outputof the units and their associated couplers is unbalanced with respect toground, and since the goniometer, as will be de- 6-9 respectively.

scribed hereinafter, while symmetrical in relaeter, to interpose betweenthe couplers and the goniometer, means for converting the potentialoutput of the couplers into balanced-to-ground potentials. For thispurpose, the output of couplers 8 and 'l is fed to anunbalanced-to-balanced transformer l0 while the output of couplers B and9 is fed to a similar type of unbalanced-tobalanced transformer il. Anysuitable type of such transformer may be employed such as for example,the type herein illustrated including a pair of coaxial lines I2 and I3havingtheir inner conductors le and l5 connected together at adjacentends IS thereof and having the input energy, as for example, fromcouplers 6 and'v'l applied to the outer conductors at said adjacent endsI6 and a ground connection to said outer conductors made at points Il onsaid outer conductorsequidistantly remote from point lli, this distancevarying in accordance with the frequencies involved and otherparameters. The free ends i8 and i9 of the inner conductors are thebalanced-to-ground output lines of said transformer.

The goniometer 5 includes two stators 20 and 2l each consisting of twoplates 22 and 23, and 2d and 25 respectively. Output lines i8 and i3 oftransformer in are coupled to plates 22 and 23 and output lines i8 andi9 of transformer .il are coupled to plates 25 and 25. Stators 20 and 2lare cylindrical and are arranged toward opposite ends of and surroundingan elongated cylindrical rotor 2@ which is coaxial with the stators.Stator plates 22 and 23 are substantially semicircular in cross section,and stator plates 24 and 25 arelikewise semi-circular in cross section,with a small space 21 extending longitudinally of the rotor between thestator plates of each stator. Likewise the rotor 26 includes twosemi-circular plates 28 and 29 winch are similarly separated from eachother by a narrow space 30.

The output of the goniometer is taken off rotor plates 28 and 29 bymeans of a capacitive arrangement midway between the stators includingdisks 3| and 32, shown schematically in Fig. 1,- whch rotate with therotor, disk 3l being electrically connected to rotor plate 28 and disk32 being electrically connected to rotor plate 29. Disks 3l and 32 arecontinuously capacitively coupled to stator plates 33 and 3Brespectively which in turn are coupled to the direction finding receiver35. i

In order that the rotor. plates may sinusoidally derive the energyapplied to the stators, the stator plates are cut back as indicated at36 so that .as the rotor plates rotate and move out of sacaste couplingrelationship with the stator plates, they do so sinusoidally.

While in-Fig. 1 the stator plates are shown as being aligned, this ismerely for the sake of clarity and as will be seen in Fig, 2, the platesof stator 2| are rotated 90 with respect to the plates of stator 20.

The output of receiver 35 is applied through couplers 31 and 38respectively to the vertically deilecting plates 39 and the horizontallydeecting plates 40 respectively of the cathode ray oscillograph tube 4|and to the grid 42 of said tube. To produce a circular trace on thescreen of the Y cathode ray oscillograph tube 4| a two-phase are atright angles to each other have alternat-A ing current energy inducedtherein in two diilerent phases correspondingly related to each other or90 out of phase. The outputs of stationary coils 48 and 49 are fedthrough couplers 31 and 38 to the deflecting plates of the cathode rayoscillograph tube 4| to produce a circular sweep. The rotor of thegenerator 43 and the rotor of the goniometer 5 are both driven by asuitable motor 5U. The motor 50, goniometer 5 and generator 43 arearranged together to form a single, compact unit which may be readilyassembled or disassembled, This unit is best seen in Fig. 2.

Referring now to Fig. 2 the goniometer 5 includes a housing 5| with therotor 26 being journalled at opposite ends thereof in ballbearing races52 and 53 set in the end walls 54 and 55 of the housing. The plates ofstator 28 and the plates of stator 2l are supported in intermediatewalls 56 and 51 respectively by means of for example, collars 58preferably of insulating material. The stators are fastened to theircollars so as to maintain the space 21 between the plates of each statorand so that stator 2| is rotated at a 90 angle to stator 20, this anglebeing measured circumferentially in the direction of curvature of saidstator members. The stator platesmay be connected to the collars by anysuitable means as for example, screws 59.

The rotor plates 28 and 29 are connected to rotating disks 3| and 32respectively, which disks are in continuous capacitive couplingrelationship with the stator plates 33 and 34, The details of theconstruction of the stator plates and 2|, the rotor 26 and thecapacitive coupling arrangement are best seen in Figs. 3 and 4.

Referring now Ato Fig. 3, it will be seen that the stator plates 24 and25 of stator 2| are chamfered at the space 21 separating them so as toreduce the capacity between said plates at these ends to a minimum. Thisis also true of the plates of stator 22. Rotor plates 28 and 29 are verythin and may be in the form of a metallic film or layer deposited on acylindrical member 60 of .Bakelite or some other suitable insulatingmate'- rial, and these plates, as indicated at 30, are separated fromeach other.

Referring to Fig. 4, the arrangement of rotat ing disks 3| and 32 isthere most clearly seen. Surrounding the insulating cylinder 60 formingpart of the rotor, are the rotor plates 28 and 29. On top of theseplates is arranged a cylindrical layer 6| of insulating material, on topof which the disks 3| and 32, together with their base portions 62 and63, are arranged. Disks 3| and 32, together with their base portions,may be machined out of a solid piece of cylindrical metal. Electricalcontrol between these disks and the rotor plates associated with themmay be made by any suitable means. For example at one point of itscircumference, the base Portion 83 has a metallic tab 84 with a threadedopening 85 in which an internally and externally-threaded member 88 isscrewed down on a peered male member 81 extending upwardly through theinsulating member 40. The member 88 presses down upon the rotor plate 29and makes electrical contact between it and the base portion 83 of thedisk 32. A similar arrangement is provided for disks 3| and its baseportion 82.

Referring back to Fig, 2, and the rest of the mechanical construction ofthe unit including the motor 50. goniometer 5 and generator 43, motor 88is demountably attached by means of screws 68, through the housing 5|,and is mechanically coupled to the rotor 26 of goniometer 5 by means ofa clutch arrangement 89, consisting of two plates 18, secured to theshafts of the motor, and of the goniometer rotor respectively andmechanically coupled together by means of a pin 1I in one of said platesextending into a key or slot 12 in the other of said plates. At theopposite end of goniometer 5 the generator 43 is demountably secured bymeans of screws 13 to said end o! the housing 5| of goniometer 5, andmay also be surrounded by another housing 14. The rotor shaft 15 of thegenerator 43 is driven by the rotor of goniometer 5 through the mediumof arrangement 16, similar to the arrangement 88. It will be seen thatthe shaft of the goniometer rotor, generator rotor and the motor rotorare all aligned. Suitable sockets for connections to the interior of thegoniometer and the rest of the unit are provided, as for example, socket11 through which power connections are made to the motor 50 and to thegenerator 43; sockets 18 and 19 through which connections are made tostators 20 and 2| respectively, and output plug and socket 83 throughwhich the output of the rotor is obtained.

From the foregoing description it will be seen that while the goniometer5 is a symmetrical arrangement with respect to the stators balanced onopposite sides of the rotor and the output capacitive coupling means inthe center of the rotor, it is not altogether symmetrical with respectto the housing 5| and therefore to ground, as can be seen in Fig. 2. Dueto the use of transformers i0 and Il, this does not aiect the balance ofthe output of goniometer 5, The input to the goniometer is symmetrical,that is, the antenna system, the length of the input lines and thevalues of the balancing transformers III and Such symmetry becomesnecessary at higher frequencies for accurate operation.

While we have described above the principles of our invention inconnection with specific apparatus, it is to be clearly understood thatthis description is made only by way of example and not as a limitationon the scope of our invention 'as deilned in the accompanying claims.

We claim:

1. A capacitive goniometer comprising a cylindrical rotor and twocylindrical stators surrounding said rotor and coaxial therewith, saidstators being spaced from each other and positioned toward opposite endsof the rotor, each of said stators and said rotor consisting of twocircum-V ferentially-spaced conductive plates substantially arcuate incross section with the plates of one stator circumferentially rotatedsubstantially 90 with respect to the plates of the other stator, andmeans for coupling the plates of the rotor to output terminals.

2'. A capacitive goniometer according to claim 1 wherein said statorplates are shaped with respect to said rotor plates so as to provide forthe sinusoidal variation of coupling between said rotor plates and saidstator plates as the rotor is rotated.

3. A capacitive goniometer according to claim 1 wherein said couplingmeans are capacitive and are arranged intermediate said stators.

4.- In a direction ilnder the combination comprising an antenna systemwhose output is unbalanced with respect to ground. a goniometercomprising a cylindrical rotor and two cylindrical stators coaxial withsaid rotor and axially spaced apart along said rotor equidistant fromthe middle thereof and a metallic housing about said rotor and stators,coupled to ground and asymmetrical zu with respect to said rotor andstators, and means for coupling said antenna system output to saidgoniometer including an unbalanced-to-balanced transformer.

5. In a direction iinder, a unit comprising a goniometer having acylindrical rotor and two coaxial cylindrical stators spaced apart anequal distance from the middle of said rotor. a motor for driving saidrotor rdemountably arranged with its shaft aligned with said rotor, atwo phase generator for generating voltages tor pro- .other in an axialdirection with respect to said rotor and coupled thereto,.each of saidstators being cylindrical and coaxial with said rotor, each of saidstators and said rotor consisting essentially of twocircumferentially-shaped conductive plates substantially arcuate incross section and said coupling means including means for separatelycoupling each of said plates of said rotor to separate output terminals.

- F. O. CHESUS.

FRANK G. THOMAS. C. S. BEDNASH.

REFERENCES CITED The following references are of record in the file ofthis patent:

